The present invention is in the field of imaging systems. More particularly, the present invention provides an apparatus and method for clamping the leading edge of a supply of recording media, such as a printing plate, on the external drum of an imaging system.
In external drum imaging systems, a movable optical carriage is commonly used to displace an image recording source in a slow scan direction while a cylindrical drum, having recording media mounted on an external surface thereof, is rotated with respect to the image recording source. The drum rotation causes the recording media to advance past the image recording source along a fast scan direction that is substantially perpendicular to the slow scan direction.
The image recording source may include an optical system for generating one or more imaging beams that are scanned across the surface of the recording media. Each imaging beam may be separately modulated according to a digital information signal representing data corresponding to the image to be recorded.
The recording media to be imaged by an external drum imaging system is commonly supplied in discrete, flexible sheets, hereinafter collectively referred to as xe2x80x9cprinting plates.xe2x80x9d Each printing plate may comprise one or more layers supported by a support substrate, which for many printing plates is a plano-graphic aluminum sheet. Other layers may include one or more image recording (i.e., xe2x80x9cimageablexe2x80x9d) layers such as a photosensitive, radiation sensitive, or thermally sensitive layer, or other chemically or physically alterable layers. Printing plates that are supported by a polyester support substrate are also known and can be used in the present invention. Printing plates are available in a wide variety of sizes, typically ranging, e.g., from 9xe2x80x3xc3x9712xe2x80x3, or smaller, to 58xe2x80x3xc3x9780xe2x80x3, or larger.
Many clamping systems are available for holding the leading edge of a printing plate on the external drum of an imaging system. One example of a leading edge clamping mechanism is disclosed in U.S. Pat. No. 6,412,413, incorporated herein by reference. Although the leading edge clamping mechanism disclosed in this reference is highly effective, it has several drawbacks. For example, the leading edge clamping mechanism uses a fixed actuator to selectively open and close a clamping portion. As such, the clamping portion can only be opened and closed when it is positioned at a single circumferential position of the external drum (i.e., under the fixed actuator). Further, the leading edge clamping mechanism is a fairly complex mechanical assembly that has a high part count and is expensive to produce.
The present invention provides an apparatus and method for clamping the leading edge of a printing plate on the external drum of an imaging system.
Generally, the present invention provides an apparatus, comprising:
a spring segment disposed on the external drum, wherein the spring segment may be selectively displaced between a clamping position for clamping the leading edge of the printing plate against the external drum and a release position; and
an inflatable member positioned between the spring segment and the external drum for displacing the spring segment between the clamping position and the release position.
The present invention further provides a method comprising:
selectively displacing a spring segment between a clamping position for clamping the leading edge of the printing plate against the external drum and a release position; and
displacing the spring segment between the clamping position and the release position using an inflatable member positioned between the spring segment and the external drum.
The present invention additionally provides an imaging system comprising:
an external drum for supporting a printing plate;
a system for recording image data onto the printing plate; and
a leading edge clamping apparatus for clamping a leading end of the printing plate on the external drum, the leading edge clamping apparatus including:
a spring segment disposed on the external drum, wherein the spring segment may be selectively displaced between a clamping position for clamping the leading edge of the printing plate against the external drum and a release position; and
an inflatable member positioned between the spring segment and the external drum for displacing the spring segment between the clamping position and the release position.
The present invention further includes a leading edge clamping apparatus for clamping a leading end of a printing plate on an external drum of an imaging system, comprising:
an inflatable member; and
a shield that may be selectively displaced by the inflatable member between a clamping position for clamping the leading edge of the printing plate against the external drum and a release position.
The present invention also provides a leading edge clamping apparatus for clamping a leading end of a printing plate on an external drum of an imaging system, comprising:
a groove formed in the external drum, wherein a wall of the groove serves to register the leading edge of the printing plate on the external drum; and
an inflatable clamp positioned in the external drum adjacent a side of the groove, wherein the inflatable clamp may be selectively displaced between an inflated, clamping position for clamping the leading edge of the printing plate to the external drum and a deflated, release position.
The present invention further provides a leading edge clamping apparatus for clamping a leading end of a printing plate on an external drum of an imaging system, comprising:
an inflatable member positioned between a spring segment and the external drum for displacing the spring segment between a clamping position and a release position.